AB0032 CHARACTERIZATION OF PERIPHERAL BLOOD B-CELL SUBSET IN UNTREATED PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS AND SYSTEMIC SCLEROSIS
Authors: E. Gerasimova, D. Tabakov, A. Aleksankin, R. Shayakhmetova, T. Popkova, A. Avdeeva
Journal: Annals of the Rheumatic Diseases (2022)

Background B-cells play a critical role in the regulation of systemic autoimmune diseases pathogenesis, that extends beyond antibodies production. Objectives To examine В-cell subsets in peripheral blood of patients (pts) with untreated systemic lupus erythematosus (SLE) and systemic sclerosis (SSc), to analyze of their associations with disease-specific autoantibodies. Methods Thirty six untreated SLE pts (31F/5M) and 32 untreated SSc pts (25F/7M) were enrolled. SLE pts had median age of 37(range)(32-41)years, disease duration of 3.5(1-11)years, SLEDAI 2K of 7(4-8), BILAG of 14,5(10,2-23). SSc pts had median age of 42(38-50)years, disease duration of 3.5(1-10)years, Disease Activity EScSG of 2.5 (1-3.2). The control group consisted of 29 volunteers (23F/6M, median age 38(35-48)years. CD19+B cells, memory B cells (CD19+CD27+), switched memory B cells (CD19+CD27+IgD-), non-switched memory B cells (CD19+CD27+IgD+), naive (CD19+CD27-IgD+), double-negative (CD19+CD27-IgD-), transitional (CD19+CD38++CD10+IgD+CD27-) B cells, and plasmablasts (CD19+СD38+++CD27+IgD-CD20-) were analyzed using multicolor flow cytometry. Results Differences in the median percentage and of absolute B-cells subset levels in untreated pts with RA and SLE were not found. The absolute counts of memory B cells (CD19+CD27+), switched memory B cells (CD19+CD27+IgD-), transitional B cells (CD19+CD38++CD10+IgD+CD27-), and plasmablasts (CD19+СD38+++CD27+IgD-CD20-) were higher in SLE and SSc pts compared to healthy donors, p&lt;0,01 for all cases. The absolute counts of double-negative B cells (CD19+CD27-IgD-) were lower in SLE pts than in donors, р=0,03 (Table 1). At significant correlation was found in SLE pts between anti-dsDNA levels and absolute counts of the following B-cell subtypes: CD19+B cells (r=0,72), memory B cells (CD19+CD27+) (r=0,76), switched memory B cells (CD19+CD27+IgD-) (r=0,75) and naive B cells (CD19+CD27-IgD+) (r=0,73); the a-Sm levels and absolute counts of the switched memory B cells (CD19+CD27+IgD-) (r=0,51); the antibodies to cardiolipin (aCL) IgG levels and absolute counts of CD19+B cells (r=0,64), and with naive B cells (CD19+CD27-IgD+) (r=0,59), p&lt;0,01 for all cases. There was a correlation between the anti-topoisomerase-1 antibodies (a-Topo-1) and the absolute counts of double-negative B cells (CD19+CD27-IgD-) (R=0,62, p=0,01) in SSc pts. Table 1. Levels of the blood B-cell subsets in SLE pts, SSc pts and in control. Parameters, n (х10 9 /l) SLE SSc Control group CD19+B cells 0,15 (0,12-0,25) 0,14 (0,12-0,20) 0,1 (0,08-0,2) memory B cells (CD19+CD27+) 0,036(0,031-0,006) * 0,042(0,027-0,053) * 0,003(0,001-0,007) * switched memory B cells (CD19+ CD27+IgD-) 0,02 (0,016-0,046) * 0,026 (0,017-0,034) * 0,01 (0,005-0,02) * non-switched memory B cells (CD19+CD27+IgD+) 0,012(0,007-0,027) 0,016(0,01-0,027) 0,02(0,01-0,04) naive B cells (CD19+CD27-IgD+) 0,09 (0,06-0,2) 0,09 (0,06-0,16) 0,1 (0,06-0,1) double-negative B cells (CD19+CD27-IgD-) 0,011 (0,006-0,014) * 0,02 (0,01-0,03) 0,02 (0,01-0,02) * transitional B cells (CD19+CD38++CD10+IgD+CD27-) 0,011 (0,004-0,026) * 0,011 (0,005-0,012) * 0,0001 (0-0,0003) * plasmablasts (CD19+СD38+++CD27+IgD-CD20-) 0,001 (0,001-0,002) * 0,001 (0-0,002) * 0,0001 (0,00006-0,0003) * Note: * - Differences in B-cell subset of the control group with SLE and SSc groups. Conclusion Immunophenotyping showed similar levels of B-cell subset in untreated SLE and SSc pts, an increase in the absolute counts of memory B cells (CD19+CD27+), switched memory B cells (CD19+CD27+IgD-), transitional B cells (CD19+CD38++CD10+IgD+CD27-), and plasmablasts (CD19+СD38+++CD27+IgD-CD20-) in untreated SLE and SSc pts compared with healthy subjects. Positive correlation between the counts of В-cell subsets and values of disease-specific autoantibodies (anti-dsDNA, a-Sm, aCLIgG, a-Topo-1) suggests that B-lymphocytes may be involved in SLE and SSc pathogenesis. This work was supported by the Russian Science Foundation (Grant № 22-25-00358). Disclosure of Interests None declared